In this case, the annihilation \(\gamma \) -rays primarily result from the decay of the \(Z^{\prime }\)  into light quarks \(u\overline{u},d\overline{d}\) , \(s\overline{s}\) , which accounts for 50.6% of the decay width. It is shown in Ref. [1]} that the annihilations of
DM particles of mass between \(\sim \)  18 and \(\sim \)  26 GeV into light quarks may significantly account for the \(\sim \)  2 – 3 GeV excess.
